I suggest adding "While your shield is down, its cooldown cannot be interrupted" to Sanctuary so it will be useful with shields other than Bastion.
With high maneuverability and low cooldown, Tempest Break lends itself to avoiding damage while the shield is down. With low maneuverability and comparatively long cooldown, Sanctuary does not. Yet, damage interrupts cooldown with Sanctuary and not with Tempest Break. The result is that, if you take Sanctuary and your shield goes down, it's difficult to evade damage, and damage prevents your shield from recovering, and if the situation you're in was dangerous to break your shield, it's probably impossible to recover... unless your shield is innately immune to cooldown interruption, which only Bastion is.